Method and apparatus for a pneumatically sprung caster mechanism

ABSTRACT

A method and apparatus for a pneumatically sprung caster mechanism to provide a pneumatically controlled ride height for a platform attached to the caster. The caster is mounted to a first end of a pivoting axle, while a piston is mounted to the opposite end of the pivoting axle. The length of the piston is pneumatically controlled to rotate the pivoting axle to either increase, or decrease, the distance between the caster and the platform. Suspension is provided through interaction of the piston with an air reservoir, whereby minute variations in the length of the piston are absorbed by the elasticity of the walls of the air reservoir. A free-flow of air is facilitated such that air forced out of the piston during contraction may be collected by the air reservoir and air required by the piston during expansion may be provided by the air reservoir.

This application is a continuation-in-part of application Ser. No.11/608,708, filed Dec. 8, 2006, which is a continuation-in-part ofapplication Ser. No. 11/321,944, filed Dec. 29, 2005, which is acontinuation of application Ser. No. 11/321,970, filed Dec. 29, 2005,which is a continuation of application Ser. No. 11/317,414, filed Dec.22, 2005, the contents of which are incorporated herein by reference intheir entirety.

FIELD OF THE INVENTION

The present invention generally relates to caster mechanisms, and moreparticularly to pneumatically sprung caster mechanisms.

BACKGROUND

The proliferation of technology in today's society has created such adependence that life without it would likely cease to exist as it isknown today. For example, the convenience of communication devices suchas wireless telephones, wireless pagers, and personal digital assistants(PDAs) have facilitated visual, audible, and tactile communications tobe conducted virtually anytime and anywhere.

Portable computing devices, such as laptop computers, have alsocontributed to technology proliferation, since they allow productiveactivity in a hotel room, on an airplane, or simply in the comfort ofone's own home. Individuals, however, are not the only members ofsociety that are taking advantage of today's technology. Business unitsin virtually all fields of commerce have come to depend upon theadvancement of technology to provide the edge that is required to keepthem competitive.

A particular business entities' operations, for example, may requireprimarily static operational facilities, or conversely may requireprimarily dynamic operational facilities. Regardless of the nature ofthe business entities' operations, they will most likely depend uponadvancements in technology to maintain their competitive edge. Theoperations of disaster relief organizations, for example, may becharacterized as primarily dynamic, since the locale of a disasterrelief organizations' operations may be the epicenter of a recentearthquake, or a flood zone left in the wake of a recent hurricane.Other primarily dynamic business operations may be exemplified by thoseof a local crime scene investigation (CSI) laboratory, whose primaryactivities include the collection and analysis of forensic evidence at aremote crime scene. Other primarily dynamic business operations mayinclude those of news and movie industries, whereby collection ofdigital data is the primary objective during their respectiveoperations.

Conversely, the characterization of a particular business entities'operation may be one that is primarily static. For example,telecommunication facilities are often provided all over the world tofacilitate wireless and/or terrestrial based communications. Suchinstallations often include switch equipment rooms that include a largenumber of electronic equipment racks that have been installed to provideboth circuit switched, and packet switched, data exchange. Other formsof primarily static installations may include data migration centers,which offer large amounts of storage capability for a variety ofapplications that require data integrity.

It can be seen, therefore, that business operations conforming to eitherof the primarily static, or primarily dynamic, paradigm have occasion toprovide electronic facilities that require at least some aspects ofmobility. Primarily dynamic entities, for example, are often faced withthe daunting task of mobilizing data computation and data storagefacilities into an area that is not particularly conducive to suchoperations. A military unit, for example, may require temporary datastorage and computational facilities at a site that is primarilycharacterized by extreme conditions, such as a desert or tropicalenvironment. As such, the data computation/storage facilities requiredby the military unit are required to be mobile and operational in anenvironment that is particularly prone to at least one of hightemperature, high humidity, and/or dust contamination. Furthermore, suchan environment may not be particularly secure, nor topographicallyconducive, to the transportability of highly sensitive electronics.

Primarily static entities are also in need of mobile electronicfacilities, since such facilities may be vulnerable to equipmentfailure, or simply may be in need of equipment upgrade. As such, amobile electronic solution is needed to provide electronic equipmentreplacement, or augmentation, to fully support the replacement of failedelectronics, or to augment the current capabilities of the electronicfacility.

Traditional electronic mobility solutions, however, simply fail in manyrespects to meet the demands of today's electronic mobilityrequirements. In particular, mobile electronic solutions oftenincorporate electronic components within a motor vehicle to providemobility. Such applications, however, preclude their use within theconfines of most buildings, since access to the interiors of thosebuildings is provided through conventionally sized access doors, whichare too small to allow access by the motor vehicle to the interiors ofmost buildings. Efforts continue, therefore, to reduce the size of motorvehicle mounted electronic solutions for enhanced mobility.

SUMMARY

To overcome limitations in the prior art, and to overcome otherlimitations that will become apparent upon reading and understanding thepresent specification, various embodiments of the present inventiondisclose an apparatus and method of providing a pneumatically sprungcaster mechanism. Variation of the ride height of a platform mobilizedby the pneumatically sprung caster mechanism is facilitated, whilesimultaneously absorbing shock and vibration caused during themobilization of the platform.

In accordance with one embodiment of the invention, a pneumaticallysprung caster comprises a caster, a pivoting axle having a first endthat is coupled to the caster, a piston that is coupled to a second endof the pivoting axle and a reservoir that is coupled to the piston. Anequilibrium length of the piston is adjusted in response to air pressurecontained within the reservoir and deviations from the equilibriumlength of the piston are substantially absorbed by elastic movement ofthe reservoir.

In accordance with another embodiment of the invention, a method ofoperating a pneumatically sprung caster comprises rotating an axle abouta center axis of the axle, pneumatically controlling the rotation of theaxle by adjusting an equilibrium length of a piston coupled to a firstend of the axle, adjusting a position of a caster coupled to a secondend of the axle in response to the pneumatically controlled rotation ofthe axle. The equilibrium length of the piston is controlled by anequilibrium magnitude of air pressure contained within a reservoir.

In accordance with another embodiment of the invention, a pneumaticallysprung caster comprises a caster, where the caster is adapted to rotate.The pneumatically sprung caster further comprises a pivoting axle havinga first end that is coupled to an axis of the caster and a second endthat is coupled to a support structure, an air bladder that is coupledto the pivoting axle, a valve that is coupled to the air bladder, and areservoir that is coupled to the valve. An equilibrium length of the airbladder is adjusted in response to actuation of the valve to receive airfrom the reservoir or exhaust air from the air bladder to adjust aheight of the support structure.

BRIEF DESCRIPTION OF THE DRAWINGS

Various aspects and advantages of the invention will become apparentupon review of the following detailed description and upon reference tothe drawings in which:

FIG. 1A illustrates an exemplary mobile electronic equipment rack;

FIG. 1B illustrates an exemplary block diagram of a pneumatically sprungswivel caster mechanism that may be used in the mobile electronicequipment rack of FIG. 1A;

FIG. 1C illustrates an alternate embodiment of a mobile electronicequipment rack;

FIG. 1D illustrates an alternate embodiment of a pneumatically sprungswivel caster mechanism;

FIG. 1E illustrates a conductive platform used within the pneumaticallysprung swivel caster mechanism of FIG. 1D;

FIG. 2 illustrates an exploded view of the mobile electronic equipmentrack of FIGS. 1A and 1B;

FIG. 3 illustrates an alternate view of the mobile electronic equipmentrack of FIGS. 1A and 1B;

FIG. 4A illustrates an exemplary schematic diagram of a multi-axissuspension system;

FIG. 4B illustrates an exemplary schematic diagram of an alternate,multi-axis suspension system;

FIG. 5 illustrates an exemplary schematic diagram of an alternate,multi-axis suspension system;

FIG. 6A illustrates an exemplary flow diagram of a method of providingcoarse suspension control; and

FIG. 6B illustrates an exemplary flow diagram of a method of providingfine suspension control.

DETAILED DESCRIPTION

Generally, the various embodiments of the present invention are appliedto an electronic equipment rack that, inter alia, may provide mobilitythrough directional self-propulsion and multi-axis suspension. Theelectronic equipment rack may further provide self-powered operation andenvironmental control with wireless access, while protecting againstunauthorized access, electromagnetic interference, and dustcontamination.

In one embodiment, for example, the mobile electronic equipment rack mayutilize a two-sided platform, whereby support is provided for electroniccomponents mounted on one side of the platform and directionalpropulsion is provided on the other side of the platform. Directionalcontrol may be provided via a wired, electronic tether, or converselymay be provided via wireless control.

Accordingly, the mobile electronic equipment rack may first be fullypopulated with electronic components and then utilized as a remotelypiloted transport mechanism to transport the mobile electronic equipmentrack to any position/location that may be necessary for a givenapplication. A multi-axis suspension system may be further employedwithin the mobile electronic equipment rack to substantially eliminatethe transfer of kinetic energy to the electronic components that arecontained within the mobile electronic equipment rack duringpositioning/re-location.

In an alternate embodiment, a non-mobile electronic equipment rack maybe provided without directional self-propulsion. In this instance, amulti-axis suspension system is nevertheless employed so that kineticenergy resulting from, for example, seismic events may be substantiallyabsorbed. Non-mobile electronic equipment racks in non-stableenvironments, such as on water based vessels or off-shore oil derricks,may also be equipped with a multi-axis suspension system so as tosubstantially absorb wave induced kinetic energy.

Other, non-mobile electronic equipment rack applications may includeairborne applications, whereby kinetic energy transfers due toatmospheric turbulence may also be substantially eliminated. Still othernon-mobile electronic equipment rack applications may include motorvehicle based applications, whereby kinetic energy transfers due tonon-ideal road conditions may also be substantially eliminated.

In either of the mobile, or non-mobile, electronic equipment rackembodiments, a multi-mode, dampened suspension system is utilized. Inthe first mode of suspension, coarse suspension control is provided toeffect a weight bearing support, whereby the magnitude of supportprovided adapts to the combined weight of the electronic components andtheir respective mounting enclosure. For example, as electroniccomponents are added, the coarse suspension control adapts by increasingthe amount of opposing force that is necessary to maintain the positionof the electronic components within a coarse position range. Conversely,as electronic components are removed, the coarse suspension controladapts by decreasing the amount of opposing force that is necessary tomaintain the position of the electronic components within the coarseposition range.

In a second mode of suspension, fine suspension control is providedthrough a damper mechanism, which opposes movement and seeks to maintaina position of the payload within a fine position range. In a firstembodiment, a static, magnetorheologically (MR) controlled damper forcemay be applied to effect static dampening. In particular, a staticallycontrolled MR damper signal is provided to the damper mechanism toprovide a fixed amount of damper force to maintain the mountingenclosure within a fine position range.

In an alternate embodiment, the damper force may be adaptive, such thatthe magnitude of the damper force is set in response to an adaptive, MRfeedback control signal from, for example, a micro-electro mechanicalsystem (MEMS) accelerometer measurement device. As such, the damperforce may be adaptively increased in response to accelerometer feedbackindicating increased acceleration. Conversely, the damper force may beadaptively decreased in response to accelerometer feedback indicatingdecreased acceleration.

A third mode of suspension utilizes a combination of an air piston andan air reservoir to implement a pneumatic spring. In such an instance,the use of coiled energy springs, or any other mechanical springmechanism, is obviated, since the interaction of the air piston with theelasticity of the air reservoir combines to generate a spring-likeaction. A fourth mode of suspension utilizes elastomeric mounts havingvariable resonant frequencies, such that vibration/shock absorbingproperties of the variable frequency elastomeric mounts may be staggeredin frequency to expand the operational bandwidth of the suspensionsystem.

Once the electronic equipment rack arrives at its designatedposition/location, or conversely is operated in a non-mobile applicationas discussed above, power may be applied to the electronic equipmentrack via an external power bus, so that each electronic component withinthe electronic equipment rack may be made to be fully operational.Operational power is typically applied in an alternating current (AC)mode, which in one embodiment, may necessitate conversion to a directcurrent (DC) mode prior to application to the electronic components.

In other embodiments, however, AC power may be directly applied to theelectronic components once the AC power has been appropriatelyconditioned. Power conditioning, for example, may be applied to theincoming AC power signal, to filter electro-magnetic interference (EMI),or any other form of noise, from the incoming AC power signal. The powerconditioner may also utilize an isolation transformer to isolate theelectronic components from power surges existing within an AC powersignal received, for example, from a common power grid. Onceconditioned, the AC power may then be applied to an internal power buswithin the electronic equipment rack for consumption by the electroniccomponents.

In such instances, for example, operation of the electronic componentswithin the electronic equipment rack may be compatible (e.g., throughoperation of the power conditioner) with AC power grids operating at aplurality of amplitudes, e.g., 110 VAC or 220 VAC, and a plurality offrequencies, e.g., 50 Hz or 60 Hz. In an alternate embodiment, the powerconditioner may also be utilized in aviation applications, where thepower grid may be operating at a DC potential of 28 VDC, or conversely,115/230 VAC at 400 Hz or 480 Hz.

Additionally, any noise that may be propagated from the electroniccomponents to the internal power bus may also be filtered by the powerconditioner, so that other equipment operating from the common powergrid may be substantially free of noise contamination that may begenerated by the electronic components. Furthermore, the electronicequipment rack may be fully encapsulated within an environment proofenclosure, which may be lined with an EMI protective shield so as tolimit the amount of EMI propagating into, or from, the electronicequipment rack.

The environment proof enclosure may also serve to maintain theelectronic equipment rack within a substantially constant operationaltemperature range. In such an instance, the temperature within theenvironment proof enclosure is held substantially constant irrespectiveof the temperature variation outside of the environment proof enclosureand irrespective of the amount of heat generated by the electroniccomponents operating within the electronic equipment rack.

In one embodiment, a heating, ventilation, and air conditioning (HVAC)unit may be mounted on, any side of the environment proof enclosure. Aninternal channel, or ducting system, may be utilized to direct heatexchanged, i.e., cooled, airflow from the HVAC unit toward the oppositeend of the electronic equipment rack. The cooled air is then allowed toflow upward, so that the electronic components operating within theelectronic equipment rack may draw the cooled air into their respectiveinteriors for cooling.

Once the air conditioned air is drawn into the individual electroniccomponent interiors, heat is exchanged from the individual electroniccomponents to the cooled airflow to effectively maintain the electroniccomponents operational within their respective temperature limits. Theheated air may then be vented from the individual electronic componentsand collected at the other end of the electronic equipment rack forcooling by the HVAC unit.

In addition to maintaining air temperature within the environment proofenclosure, humidity may also be controlled by the HVAC unit throughappropriate humidification control via, e.g., mechanical refrigerationor desiccant-based dehumidification. Thus, the HVAC implemented humiditycontrol may correct for excessively high humidity, so that corrosion ofelectrical contacts within the environment proof enclosure is virtuallyeliminated. Conversely, the HVAC implemented humidity control may alsocorrect for excessively low humidity, so that electrostatic dischargeeffects (ESD) may be mitigated.

Since the environmental control system is a closed loop system, dustcontrol is inherently implemented within the environment proofenclosure. That is to say, for example, that heat is exchanged withoutintroduction of external air into the environment proof enclosure. Assuch, not only is dust prevented from entering the environment proofenclosure, but any dust that may be trapped within the environment proofenclosure prior to sealing, is immediately captured by an internal dustfilter during circulation of the heat exchanged airflow from the HVACunit.

Data egress from the environment proof enclosure and data ingress to theenvironment proof enclosure may be accomplished, for example, via amultiple-in, multiple-out (MIMO) wireless interface. In particular,multiple antennas may be used to provide a diverse, wireless accesspoint (WAP), whereby multipath signals may each be received andcoherently combined for added signal strength. As such, the range ofaccess and data rate may be considerably increased as compared, forexample, to the IEEE 802.11a, 802.11b, and 802.11g family of wirelesscommunication specifications.

Data egress and ingress to the environment proof enclosure may also beaccomplished via a keyboard, video, mouse (KVM) wireless switch. The KVMwireless switch may be used, for example, to allow access to networkmanagement and control features that may be provided by the electroniccomponents hosted within the environment proof enclosure. It should benoted, that both the MIMO and KVM interfaces allow access to theelectronic components, while the electronic components are operationalwithin the environment proof enclosure. An alternate, wired interfacemay also be used in addition to, or instead of, the KVM and/or MIMOwireless interfaces for essentially the same purposes.

Security and safety features may also be incorporated within theelectronic equipment rack, so that unauthorized access to the datastorage, computational resources, or any other application of theelectronic components, may be prohibited. Other security features mayemploy a multi-user/multi-function access control to allow permissionfor specific users to perform specific functions. For example, specificusers may be individually authorized to mobilize and/or energize themobile electronic equipment rack. Specific users may also beindividually authorized to access the mobile electronic equipment rackvia electronically controlled access hatches should it be encapsulatedwithin an environment proof enclosure.

Turning to FIG. 1A, an exemplary embodiment of a mobile electronicequipment rack is illustrated. Directional self-propulsion may befacilitated by mobility control device 106, which may be mounted to abottom surface of platform 120. Mobility control device 106 may beelectro-mechanically controlled via, for example, a DC drive motor (notshown), to convert mobility control signals into directional propulsionto maneuver the mobile electronic equipment rack into its designatedposition/location.

Mobility control signals may be provided to mobility control device 106through a wireless, or wired, medium. Wired access, for example, may besupplied via a tether control mechanism (not shown) that may be attachedvia patch panel 116, or some other interface. One of input/output (I/O)interface connectors 118, for example, may facilitate exchange ofmobility control signals to/from mobility control device 106.

A wide variety of mobility control information may be accepted bymobility control device 106 to control such mobility aspects asvelocity, direction, and acceleration/deceleration. A center wheeldrive, for example, may be utilized to receive directional controlsignals to provide 360 degree maneuverability of the mobile electronicequipment rack via rive wheels 126. In particular, drive wheel 126 andthe opposing drive wheel (not shown) are independently activated via anarticulated transaxle drive, which facilitates a 0 degree turn radius.Casters 128 are also provided for stability, both during transport, aswell as during stationary operation. As discussed in more detail below,user's wishing to maneuver the mobile electronic equipment rack viamobility control device 106 may first be required to authenticatethemselves through security control features implemented within themobile electronic equipment rack.

Turning to FIG. 1B, an alternate embodiment is illustrated, wherebycasters 128 may provide an additional mode of suspension, whilesimultaneously providing an adjustable ride height of the mobileelectronic equipment rack. In particular, the pneumatically sprungswivel caster mechanism of FIG. 1B may provide an independentlycontrolled ride height for each corner of the mobile electronicequipment rack depending upon the terrain.

For example, should the mobile electronic equipment rack be required totraverse an incline, the fore mounted pneumatically sprung swivelcasters may be commanded to a ride height that is higher than a rideheight of the aft mounted pneumatically sprung swivel casters, so as toprovide increased ground clearance at the leading edge of the mobileelectronic equipment rack as compared to the trailing edge. Such rideheight control may be adapted, for example, to prevent striking theinclined surface with the bottom portion of the mobile electronicequipment rack during traversal of the incline.

Caster 154 is mounted to pivoting axle 158 and is allowed to rotateabout axis 188 to facilitate mobility of the mobile electronic equipmentrack. Air piston 166 is mounted to pivoting axle 158 via mount 184,which is located at the opposite end of pivoting axle 158 with respectto caster 154. Air piston 166 may be programmably adapted by controller156 to either contract its length along axis 168, or expand its lengthalong axis 170 so as to cause pivoting axle 158 to pivot about axis 186.

If air piston 166 is programmed to contract its length along axis 168,for example, then pivoting axle 158 is caused to rotate in acounter-clockwise direction about axis 186, which causes mount 184 tomove upward along axis 168. In response, caster 154 is caused to movedownward along axis 170, which ultimately causes swivel plate 172 toincrease its position along axis 190 with respect to caster 154. Thus,given that swivel plate 172 is mounted to one corner of the bottomsurface of platform 120 of the mobile electronic equipment rack of FIG.1A, then that corner is caused to elevate its position with respect tothe surface that caster 154 is rotating upon.

If, on the other hand, air piston 166 is programmed to expand its lengthalong axis 170, then pivoting axle 158 is caused to rotate in aclockwise direction about axis 186, which causes mount 184 to movedownward along axis 170. In response, caster 154 is caused to moveupward along axis 168, which ultimately causes swivel plate 172 todecrease its position along axis 190 with respect to caster 154. Thus,given that swivel plate 172 is mounted to one corner of the bottomsurface of platform 120 of the mobile electronic equipment rack of FIG.1A, then that corner is caused to lower its position with respect to thesurface that caster 154 is rotating upon.

It can be seen, therefore, that each corner of the mobile electronicequipment rack of FIG. 1A may be independently programmed by controller156 to effect an adjustable ride height at each corner of the mobileelectronic equipment rack. Ride height contact switches 160 and 162 maybe used by controller 156 to detect the angular position of pivotingaxle 158.

A maximum ride height, for example, may be detected by controller 156,should contact switch 160 of ride height switch 164 lose contact withits mating contact on pivoting axle 158 when air piston 166 iscontracted to its minimum length along axis 168. A minimum ride height,on the other hand, may be detected by controller 156, should contactswitch 162 of ride height switch 164 lose contact with its matingcontact on pivoting axle 158 when air piston 166 is expanded to itsmaximum length along axis 170. When both contact switches 160 and 162make contact with their respective mating contacts, then pivoting axle158 may be determined by controller 156 to be relatively parallel to thesurface that caster 154 is rotating upon.

Expansion/contraction of air piston 166 is accomplished via controller156 by commanding increased/decreased air pressure within air reservoir176. For example, increased air pressure may be commanded by controller156 by: 1) selecting valve 180 as an intake valve; and 2) causingcompressor 182 to inflate air reservoir 176 via air tubing 174, whichsubsequently expands air piston along axis 170 by increasing airpressure within air piston 166. Conversely, decreased air pressure maybe commanded by controller 156 by: 1) selecting valve 180 as an exhaustvalve; and 2) deflating air reservoir 176, which subsequently contractsair piston along axis 168 by decreasing air pressure within air piston166.

An additional mode of suspension is provided by the pneumatically sprungswivel caster mechanism of FIG. 1B through the interaction of air piston166, air reservoir 176, and air tubing 174. In particular, once anequilibrium length of air piston 166 has been established, minutevariations in the length of air piston 166 may be absorbed through theelasticity of the walls of air reservoir 176. In one embodiment, forexample, the walls of air reservoir 176 may be constructed of an elasticcomposition, such as rubber, to allow expansion and contraction of thewalls of air reservoir 176 along axis 178. Air tubing 174 facilitates afree-flow of air to be exchanged between air piston 166 and airreservoir 176, such that air forced out of air piston 166 duringcontraction may be collected by air reservoir 176 and air required byair piston 166 during expansion may be provided by air reservoir 176. Itshould be noted that the walls of air reservoir 176 do not necessarilyexpand and contract along axis 178, but may expand and contract in anydirection defined by the elasticity of the walls of air reservoir 176.

A slight contraction of air piston 166 along axis 168 causes aresponsive slight expansion of the walls of air reservoir 176.Conversely, a slight expansion of air piston 166 along axis 170 causes aresponsive slight contraction of the walls of air reservoir 176. Due tothe elasticity of air reservoir 176, however, the length of air piston166 is returned to its equilibrium length as defined by the amount ofair pressure contained within air reservoir 176. Thus, a spring-likeoperation is created through the interaction of air piston 166 and airreservoir 176, whereby the elasticity of the walls of air reservoir 176serves to absorb minute variations in the length of air piston 166 thatmay be caused by fluctuations of caster 154 along axis 190 in responseto the terrain being traversed by caster 154.

Through interaction of air piston 166 and air reservoir 176, therefore,dynamic variations in the position of caster 154 along axis 190 may beabsorbed by the elasticity of the walls of air reservoir 176. As such,vibration and shock that may be caused by traversal of rough terrain maybe substantially absorbed by the interaction of air piston 166 and airreservoir 176, instead of being transferred to swivel plate 172. Giventhat swivel plate 172 may be mounted to the bottom surface of platform120 of the mobile electronic equipment rack of FIG. 1A, thepneumatically sprung swivel caster mechanism of FIG. 1B may furtherreduce the magnitude of vibration and shock that is transferred to thepayload contained within the mobile electronic equipment rack of FIG.1A.

Turning to FIG. 1C, an alternate mobility mechanism is exemplified,whereby the mobile electronic equipment rack may be transported via atrack drive system. Such a mobility system, for example, allowstraversal of terrain that would not otherwise be facilitated by thecaster mechanisms discussed above in relation to FIGS. 1A and 1B. Inparticular, given that the gross weight of the mobile electronicequipment rack may exceed several thousands of pounds, a caster basedmobility mechanism would prove unacceptable in particularly softterrain, since each caster would most likely sink into the soft terrain,as opposed to rolling over the top of it. A track drive system, on theother hand, allows the weight of the mobile electronic equipment rack tobe more evenly distributed, thus facilitating traversal over softterrain, as well as other more extreme terrain that is not conducive tocaster based mobility systems.

Turning to FIG. 1D, an alternate embodiment of a pneumatically sprungswivel caster mechanism is provided that utilizes air bladder 134 ratherthan air piston 166, as discussed above in relation to FIG. 1B, toprovide ride height control. In addition, both embodiments of FIGS. 1Band 1D provide a tip-control mechanism, which as discussed in moredetail below, operates to counteract any forces that may be applied thatwould cause the mobile electronic equipment rack of FIG. 1A to tip over.

For example, should a force be applied to one side of the mobileelectronic equipment rack, the ride height control associated with thatside of the mobile electronic equipment rack operates to decrease theride height associated with that side. Conversely, the ride heightcontrol of the opposite side operates to increase the ride heightassociated with the opposite side. As a result, the mobile electronicequipment rack “pushes back” against, or opposes, the force that wouldotherwise cause the mobile electronic equipment rack to tip over.

Caster 154 of FIG. 1D is mounted to pivoting axle 158 and is allowed torotate about axis 188 to facilitate mobility of the mobile electronicequipment rack. Air bladder 134 is mounted to pivoting axle 158 via axis188. A second end of pivoting axle 158 is coupled to support structure142. Air bladder 134 is programmably adapted by controller 156 to eithercontract its length along axis 190, or expand its length along axis 190,so as to cause platform 138 and support structure 142 to move up anddown along axis 190.

It can be seen, therefore, that each corner of the mobile electronicequipment rack of FIG. 1D may be independently programmed by controller156 to effect an adjustable ride height at each corner of the mobileelectronic equipment rack, since each corner of the mobile electronicequipment rack is attached to platform 138. To facilitate ride heightdetection, switches 150 and 194 may be utilized to detect the positionof magnet 192, whereby switches 150 and 194 are implemented as anelectrical switch, such as a reed switch, that is actuated in thepresence of, e.g., a magnetic field.

A maximum ride height, for example, may be detected by controller 156,should reed switch 150 be activated when magnet 192 is brought intoclose proximity to switch 150. A minimum ride height, on the other hand,may be detected by controller 156, should reed switch 194 be activatedwhen magnet 192 is brought into close proximity to switch 194. When bothreed switches 150 and 194 are in either of a normally closed, ornormally open state, when not in the presence of a magnetic fieldgenerated by magnet 192, then air bladder 134 may be determined to be inan equilibrium position.

Expansion/contraction of air bladder 134 is accomplished via controller156 by appropriate control of intake/exhaust valve 180. For example,increased air pressure within air bladder 134 may be commanded bycontroller 156 by: 1) selecting valve 180 as an intake valve; and 2)causing air from air reservoir 136 to fill air bladder 134 via airtubing 140, which subsequently expands air bladder 134 along axis 190 byincreasing air pressure within air bladder 134. Conversely, decreasedair pressure may be commanded by controller 156 by: 1) selecting valve180 as an exhaust valve; and 2) deflating air bladder 134, whichsubsequently contracts air bladder 134 along axis 190 by decreasing airpressure within air bladder 134. It is noted that air tubing 140 betweennipple 144 and air bladder 134 is not shown.

It is further noted that nipple 144 allows rotation of contact platform198 as caster 154 swivels. In particular, conductive traces 152 areetched into contact platform 198, as illustrated in FIG. 1E, asconcentrically shaped circles such that electrical communication betweenthe control leads extending from reed switches 150 and 194 and thecorresponding control inputs to controller 156 is facilitated even whilecaster 154 swivels.

It should be noted that each component illustrated in FIG. 1D rotates360 degrees, or swivels, in a circular direction that is orthogonal todirection 190, except components 182, 136, and possibly components 180and 156. Contacts 148, therefore, are movably coupled to, or sweepalong, conductive traces 152 as caster 154 swivels, so as to maintainelectrical communication between electrical contacts 146 and controller156. Each conductive trace 152, for example, is electrically coupled toa corresponding electrical contact 146, so as to maintain a one-to-onecorrespondence between each electrical contact 146 and a correspondingconductive trace 152.

Braking mechanism 196, such as a solenoid brake, may be similarlyactuated by controller 156 through electrical communication betweencontroller 156 and braking mechanism 196 via contact platform 198. As aresult, braking mechanism 196 may prevent rotation of caster 154 throughactivation of a mechanical means (not shown) either at the outer surfaceof caster 154, or at axle portion 188.

Compressor 182 of FIG. 1D operates similarly as discussed above inrelation to FIG. 1B, except that compressor 182 does not react to astroke length of air bladder 134. Instead, compressor 182 automaticallyseeks to maintain a threshold amount of air pressure within reservoir136 for proper operation. Furthermore, reservoir 136 of FIG. 1D does notinclude elastic side walls as does reservoir 176 of FIG. 1B. Instead,reservoir 136 provides rigid side walls, where the elasticity of airbladder 134 instead provides the added dimension of suspension, sinceair bladder 134 expands and contracts as caster 154 traverses roughterrain.

It should be noted that application of the pneumatically sprung swivelcaster mechanisms of FIGS. 1B and 1D is not limited to the mobileelectronic equipment rack of FIG. 1a . Rather, the pneumatically sprungswivel caster mechanisms of FIGS. 1B and 1D may be applied across allapplications requiring caster mobility with ride height and anti-tipfunctionality, such as tool box carts, luggage carts as utilized toload/unload luggage into/from aircraft, manufacturing facility carts,etc.

Returning to FIG. 1A, operational power may be supplied to the mobilitycontrol systems discussed above as either electrical power, via DCbatteries or fuel cells, or conversely, as hydraulic power, via ahydraulic pump. As discussed above, power conditioner 108 may receiveany one of a variety of DC and/or AC input power signals. If DC issupplied, for example, then the DC power may be directly applied, orregulated and then applied, to recharge the DC batteries (not shown),which may be responsible for delivering current to activate thetransaxle drive (not shown) of mobility control device 106. Alternately,AC power may be accepted by power conditioner 108 and subsequentlyrectified to produce the DC power levels required to recharge the DCbatteries (not shown). Fuel cells may also be utilized instead of DCbatteries to enhance the amount of power that may be generated. In oneembodiment, fuel cells may provide power to a hydraulic pump to operatethe track drive system of FIG. 1C.

Environment proof enclosure 102 may be utilized to maintain interiorcompartment 104 of the mobile electronic equipment rack within a rangeof controlled environment specifications. For example, once electroniccomponents are installed within mounting enclosure 122, access hatch 114may then be closed to seal the electronic components within atemperature controlled, substantially dust free environment.Furthermore, EMI shielding may be installed along the inner surfaces ofenvironment proof enclosure 102, or conversely environment proofenclosure 102 may be manufactured from EMI shielding material, such asfiberglass-reinforced foil, or aluminum, to substantially eliminate EMIingress/egress.

Still further, noise filtering may also be employed within powerconditioner 108, as well as patch panel 116, to substantially eliminateconduction of noise and EMI onto the power and control buses (not shown)within interior compartment 104. In particular, each connector 118 ofpatch panel 116 may be bulkhead mounted with EMI shielded gaskets andhatch 124 may further be grounded to provide an EMI shield when closed.

It should be noted, that environment proof enclosure 102 may alsoprovide protection against ballistic projectiles by appropriatelydesigning the walls of environment proof enclosure 102. For example, thewalls of environment proof enclosure 102 may be implemented with armoredmaterials such as fiberglass, or other composites, such as carbon fiber,ceramic, Kevlar®, etc. In one embodiment, protection against 9 mmprojectiles, or the equivalent, may be implemented through appropriatedesign of environment proof enclosure 102.

Access to interior compartment 104 may be provided by any one of anumber of access hatches, such as access hatch 114. As discussed above,authentication of authority to activate access hatch 114 may first berequired as a security measure. Access hatch 124 may be similarlyprovided to allow access to patch panel 116. Access to either of accesshatches 114 or 124 may be authorized/unauthorized by thedisengagement/engagement of locking mechanisms 130 and 132,respectively. The authorization being predicated upon successfulauthentication of the particular user who is requesting access.

Various security mechanisms may be employed to authenticate users priorto allowing access to interior compartment 104 and/or patch panel 118. Awireless KVM switch (not shown) mounted within interior compartment 104,for example, may receive a wireless authentication request from a user.In one embodiment, the wireless KVM switch may receive biometricinformation that is associated with the user, such as a scan of his orher fingerprint, in order to authenticate the user's access. Biometricauthentication may also include techniques for measuring and analyzingother physical and behavioral characteristics of a user. Examples ofphysical characteristics that may be used for physical authenticationare eye retina scans, facial patterns, and hand measurements.Alternatively, behavioral characteristics such as signature, gait andtyping patterns may also be used for biometric authentication. Hybridcharacteristics that share both physical and behavioral characteristics,such as voice, may also be used for biometric authentication.

In an alternate embodiment, authentication may instead be initiatedthrough activation of a security device, such as a universal serial bus(USB) based flash drive that may insert into an authenticationverification device (not shown). The authentication verification devicemay be mounted externally to environment proof enclosure 102 to allowinsertion of a security device, such as the USB based flash drive.

In another embodiment, a biometric scanner (not shown) may be installedwithin the authentication device (not shown) to obviate the need to usethe wireless KVM switch, or other security device, for userauthentication. Other embodiments may provide wireless authenticationthrough the use of radio frequency identification (RFID), Bluetoothaccess control, inductive proximity sensors, etc.

In yet another embodiment, locking mechanisms 130 and 132 may employelectronic cylinders that are void of a keyway, which precludesunauthorized access via mechanical countermeasures. Instead, thecylinders are electronically actuated by a battery powered key thatactivates the cylinder to conduct an authorization of the key foraccess. Each key may, for example, contain a list of electronic cylinderidentification codes that are compatible with the key. If theidentification code of the particular electronic cylinder is notcontained within the memory of the key, for example, then access isdenied. An audit trail may further be contained within each key andelectronic cylinder so that any access requests may be tracked over acertain period of time.

As discussed above, environment control unit 110 may be utilized tomaintain interior compartment 104 within a predetermined temperature andhumidity range. In one embodiment, environment control unit 110 may beimplemented as an HVAC unit operating within a closed circuit consistingof, for example, a compressor, an expansion valve, and two heatexchangers, e.g., an evaporator and a condenser. A volatile liquid, suchas a refrigerant, circulates through the four components and isdelivered to the compressor after having absorbed heat from interiorcompartment 104. The refrigerant exits the compressor as a hot vapor,where it is then condensed into a warm liquid. A flow control valveregulates the flow of the refrigerant, allowing it to expand into a coldliquid before returning to interior compartment 104 to complete thecycle. Air, having been cooled by the cold liquid, is then circulatedvia a ducted channel for optimal cooling of the electronic componentsmounted within interior compartment 104.

Environment control unit 110 may itself be mounted onto a hinged accesshatch that is similar to access hatch 114. As such, authenticatedegress/ingress may be allowed from/to interior compartment 104 at theopposite end of access hatch 114 to facilitate access to the rear end ofelectronic components mounted to mounting enclosure 122. It should benoted, that environment control unit 110 may also be installed on anyother side of environment proof enclosure 102 as may be required by aparticular implementation. For example, the size and weight ofenvironment control unit 110 may require that it be mounted on top ofenvironment proof enclosure 102 in order to provide optimal weightdistribution for improved stability.

Operation of electronic components mounted to mounting enclosure 122 areintended to be operated while all access hatches are secured. Given thatpatch panel 116 is implemented with water resistant connectors andattachments, however, it is understood that hatch 124 may remain openwhile the electronic equipment rack of FIGS. 1A and 1C are operational,even while operating in an environment susceptible to atmosphericprecipitation.

As discussed above, the operational power applied to power conditioner108 may be derived from AC power grids operating at a plurality ofamplitudes, e.g., 110 VAC or 220 VAC, and a plurality of frequencies,e.g., 50 Hz or 60 Hz. In alternative embodiments, power conditioner 108may also be utilized in aviation applications, where the power grid maybe operating at a DC potential of 28 VDC, or conversely, 115/230 VACoperating at 400 Hz or 480 Hz.

In any event, once the electronic components are operational, access totheir respective I/O ports may be provided in one of two formats. First,MIMO wireless access point (WAP) 112, for example, may be used to accessthe data/computational resources of the electronic components. MIMO WAP112 implements two or more antennas to send and receive informationusing, for example, orthogonal frequency division multiplexing (OFDM) tosignificantly increase the data throughput as compared to conventionalwireless access technologies.

A MIMO router may be used in conjunction with MIMO WAP 112 toprovide/retrieve information to/from the electronic components that aremounted to mounting enclosure 122. The MIMO router may support thestandard Wired Equivalent Privacy (WEP) and/or the advanced Wi-FiProtected Access (WPA) for data encryption. Additional security featuresmay also include Media Access Control (MAC) and Internet Protocol (IP)filtering for limiting network access based on MAC Address or IPAddress.

Wired access to the data/computational resources of the electroniccomponents of the mobile electronic equipment rack may also beimplemented via water resistant patch panel 116. Connectors 118 mayrepresent a wide variety of data I/O connectors, such as for example,category 5 and/or 6 connectors, as may be used to support GigabitEthernet applications. Fiber optic communications may also be supportedby patch panel 116 in support of, for example, a synchronous opticalnetwork (SONET) ring. It is appreciated that any number of I/Oconnectivity options, such as radio frequency (RF) connectors, or KVMconnectors, may also be provided by patch panel 116.

In operation, the mobile electronic equipment rack of FIGS. 1A and 1Cmay include use as a mobile, high-density server, such as a bladeserver. In particular, mounting enclosure 122 may be adapted to mount aplurality of blade server chassis, where each chassis may include aplurality of modular electronic circuit boards known as server blades.Each server blade contains one or more microprocessors, memory, andother electronics, and is generally intended for a specific application.The server blades may also provide integrated network controllers, afiber optic host bus adapter (HBA), and other I/O ports to facilitatedata exchange.

Each server blade may also include an advanced technology attachment(ATA) or small computer system interface (SCSI) disk drive. Foradditional storage, the blade servers may connect to a storage pool(via, for example, the MIMO or patch panel interface), where the storagepool is facilitated by a network attached storage (NAS), fiber channel,or Internet SCSI (iSCSI) storage area network (SAN). Blade serversmounted within the mobile electronic equipment rack of FIGS. 1A and 1Care effective to consolidate several blade servers into a single chassisand also to consolidate associated resources, such as storage andnetworking equipment, into a smaller architecture that can be managedthrough a single interface, e.g., the MIMO or patch panel interface, asdiscussed above.

Furthermore, multiple blade server chassis may be mounted and configuredfor operation before mobilization. In such an instance, pre-configuredblade servers may be mobilized in a completely secure environment,protected from vibration induced damage during transportation, andquickly energized within a temperature and humidity controlledenvironment virtually anywhere in the world. In addition, the bladeserver network may be quickly relocated in a safe, orderly, andefficient manner as may be required by many government and/or commercialapplications.

One such commercial application, for example, includes use as a storagemedium for digitized audio, graphical, and video information in supportof media, television, and motion picture operations. In particular, asnew standards are developed for digital technologies in audio, stillpictures, motion pictures, and television, digital storage solutionsbecome increasingly necessary. As such, the mobile equipment rack ofFIGS. 1A and 1C may be populated with blade servers and deployed tosupport digital video and audio storage at various stages of digitaldata operations, e.g., acquisition, production, control-room editing,transmission, and reception.

Thus, the mobile equipment rack of FIGS. 1A and 1C may be effectivelydeployed as mobile video storage servers, such that when fullyconfigured with blade servers as discussed above, may provide, forexample, up to 57 terabytes of audio/video digital storage capability.As such, wireless camera feeds to the MIMO WAP 112 of the video storageserver may be implemented during, for example, on-location filming tofacilitate direct digital storage of several days, or even severalweeks, of direct digital audio/video recordings.

Once its storage capacity has been reached, the mobile video storageserver may be relocated to a main control room, whereby direct editingof the digital content may be achieved. Conversely, the mobile videostorage server may remain deployed on-location to supportediting/playback operations at the actual filming site, wherebyediting/playback operations may be facilitated through digital dataaccess via either of MIMO WAP 112 or wired patch panel 116.

It should be noted, that the mobile electronic equipment rack of FIGS.1A and 1C may be implemented with low-profile suspension, as discussedin more detail below, which provides for a reduced height. Furthermore,the width of the mobile electronic equipment rack of FIG. 1A allowsentry into most standard sized doorways. In one embodiment, for example,physical dimensions of the mobile electronic equipment rack of FIG. 1Aprovides approximately 58″ in height, 27″ in width, and 54″ in length.Thus, access to the interiors of most standard buildings is facilitatedby the relatively small profile dimensions of the mobile electronicequipment rack of FIG. 1A, which enhances the versatility provided toits commercial, industrial, and governmental users.

Turning to FIG. 2, an exploded view of the various enclosures areillustrated, whereby a portion of environment proof enclosure 102 ispulled away to reveal mounting enclosure 122 and structural enclosure202. Also exemplified, is the rear view of patch panel 116 as well as aside view of environment control unit 110 and power conditioner 108.

As can be seen by inspection, mounting enclosure 122 is enclosed withinstructural enclosure 202. Both mounting enclosure 122 and structuralenclosure 202 are composed of an anodized metal, such as aluminum orsteel, and may be tig welded for strength, or conversely, may utilizeother coupling techniques such as bolted or clamped connections. Asdiscussed in more detail below, mounting enclosure 122 “floats” withinthe spatial confines as defined by structural enclosure 202 through theuse of a multi-axis suspension system. That is to say, for example, thatmultiple modes of support are used to create a multi-axis, variableweight, magnetorheological isolation system, which seeks to maintainmounting enclosure 122, and electronic components (not shown) mountedtherein, substantially isolated from kinetic energy transfer.

Structural enclosure 202 is “hard” mounted to platform 120 (not shown inFIG. 2), while mounting enclosure 122 is “soft” mounted to both platform120 (not shown in FIG. 2) and structural enclosure 202. As such, kineticenergy may be directly transferred to structural enclosure 202 duringtransportation, or other acceleration generation events, due to the“hard” mounting relationship between platform 120 and structuralenclosure 202. In contrast, however, substantially all of the kineticenergy that may be transferred to structural enclosure 202 along alongitudinal component as defined by directional vector 208 is virtuallyabsorbed by supports 204 and 206.

As discussed in more detail below, supports 204 and 206 may beimplemented as magnetorheological dampers, pneumatic springs, or acombination of both. In addition, while only two supports areillustrated, more support quantities may be added. In one embodiment,for example, four pneumatic springs may be situated at, or near, eachcorner of structural enclosure 202 and mounting enclosure 122, while twoMR supports may be co-located with two of the pneumatic springs toprovide damper resistance. In operation, the MR supports provide damperresistance against the transfer of kinetic energy along longitudinalaxis 208, while the pneumatic springs seek to maintain mountingenclosure 122 and its contents centered within structural enclosure 202along longitudinal axis 208.

MR supports represent a first mode of “soft” support, whereby relativemotion between mounting enclosure 122 and supporting enclosure 202 isdampened by operation of the MR supports. A first end of the MR supportsare coupled to an outer portion of mounting enclosure 122 asillustrated, while a second end of the MR supports are coupled to aninner portion of structural enclosure 202 as illustrated. The couplingbetween the outer portion of mounting enclosure 122 and the innerportion of structural enclosure 202 is said to be “soft”, sincesubstantially all of the kinetic energy that is transferred by therelative motion between mounting enclosure 122 and supporting enclosure202 is dampened by operation of the MR supports.

The MR supports utilize an MR fluid, whereby a viscosity change in theMR fluid is effected in the presence of a magnetic field toincrease/decrease the dampening effects of the MR supports. Inparticular, a control unit (not shown) transmits a pulse width modulated(PWM) signal to a magnetic coil that surrounds the MR fluid containedwithin a monotube housing of the MR supports. The PWM signal parameters,such as duty cycle and amplitude, may be predetermined through the useof a potentiometer (not shown) and may be preset to a predeterminedvalue by an appropriate voltage as selected by the potentiometer.

By increasing the duty cycle of the PWM signal through forwardpotentiometer control, for example, the control unit imparts anincreased magnitude of time varying current to the magnetic coil, whichin turn imparts an increased magnetic field around the MR fluid. Inresponse, the damper forces exerted by the MR supports increaseproportionally. Conversely, by decreasing the duty cycle of the PWMsignal through reverse potentiometer control, the control unit imparts adecreased magnitude of time varying current to the magnetic coil, whichin turn imparts a decreased magnetic field around the MR fluid. Inresponse, the damper forces exerted by the MR supports decreaseproportionally.

As discussed above in relation to the operation of the pneumatic springswivel caster mechanism of FIG. 1B, pneumatic springs may also beutilized in combination with the MR supports to provide an addeddimension of suspension. Through interaction of each air piston and airreservoir, i.e., the pneumatic spring mechanism, any variation of theposition of mounting enclosure 122 relative to structural enclosure 202along longitudinal axis 208 may be opposed. As such, the pneumaticspring seeks to maintain the position of mounting enclosure 122 withinan equilibrium position relative to structural enclosure 202 alonglongitudinal axis 208.

Turning to FIG. 3, a vertical component of isolation is illustratedalong directional vector 306. In particular, support components 302 and304 are “soft” coupled to the bottom side of mounting enclosure 122 andplatform 120 (not shown), such that support is provided to mountingenclosure 122, and each electronic component (not shown) mountedtherein, in direct proportion to the weight of the combined mountingenclosure 122 and electronic component payload. That is to say, thatsupport components 302 and 304 provide weight adaptive support along thevertical directional vector 306 in order to maintain a substantiallyfixed position of mounting enclosure 122 that is virtually independentof the combined weight of mounting enclosure 122 and associated payload.

Furthermore, support components 302 and 304 provide flexibility alonglongitudinal axis 308, in order to account for any weight discrepanciesthat exist along longitudinal axis 308. For example, electroniccomponents may be mounted within mounting enclosure 122, such that moreweight is transferred to support component 302 as compared to the amountof weight that is transferred to support component 304. In thisinstance, the amount of weight bearing support that is provided bysupport component 302 is greater than the weight bearing support that isprovided by support component 304.

Conversely, electronic components may be mounted within mountingenclosure 122, such that more weight is transferred to support component304 as compared to the amount of weight that is transferred to supportcomponent 302. In this instance, the amount of weight bearing supportthat is provided by support component 304 is greater than the weightbearing support that is provided by support component 302. Thus, ineither instance, the amount of weight bearing support that is providedby supports 302 and 304 is weight adaptive in order to maintain mountingenclosure 122 in a relatively level attitude irrespective of therelative positions of platform 120 (not shown) and/or support enclosure202.

It should be noted, that supports 302 and 304 provide an additionaldegree of freedom along an axial component as defined by directionalvector 308. In particular, supports 302 and 304 provide a degree offreedom to allow operation of supports 204 and 206 as discussed above inrelation to FIG. 2. Thus, supports 302, 304, 204, and 206 interoperatewithin a two-dimensional range of movement to provide suspension alongaxial components defined by directional vectors 306 and 308.

A third dimension of suspension along an axial component that isorthogonal to both directional vectors 308 and 306 may be provided tosubstantially isolate mounting enclosure 122 from lateral accelerationforces. In such an instance, dampening MR supports and pneumaticsprings, such as those utilized for supports 204 and 206, may be coupledbetween mounting enclosure 122 and support enclosure 202, in aperpendicular arrangement, to provide dampened/pneumatic springsuspension along a lateral axis that is perpendicular to longitudinalvector component 308 and vertical vector component 306.

In one embodiment, support components 302 and 304 may include apneumatic shock absorption device, whereby a deflection of mountingenclosure 122, due to the addition or subtraction of weight, may besensed and corrected. Magnetic sensors (not shown), for example, may bemounted to both mounting enclosure 122 and support enclosure 202 todetect a change in position of mounting enclosure 122 relative tosupport enclosure 202 along directional vector 306. In such an instance,feedback provided by the magnetic sensors (not shown) may be provided toa compressor (not shown) to inflate/deflate pneumatic support components302 and 304 so that the axial position of mounting enclosure 122relative to support enclosure 202 along directional vector 306 ismaintained within a predetermined stroke range.

An additional layer of suspension may be added, for example, to one ormore of supports 204, 206, 302, and 304. In particular, elastomericmounts may be utilized between supports 204, 206, 302, 304 and theirrespective mounting surfaces to provide an additional layer ofvibration/shock absorption. Furthermore, elastomeric compounds havingvarying resonant frequencies may be selected to optimize the operationof the suspension system. For example, given that the MR dampers areresponsive up to a nominal frequency of, e.g., 40 hertz, the resonantfrequency of each elastomeric mount may be selected to be higher thanthe operational frequency range of the MR dampers. Thus, by appropriatestaggering of resonant frequencies, elastomeric mounts may be selectedto extend the operational bandwidth of the suspension system to wellbeyond the operational frequency range of the MR dampers.

Turning to FIG. 4A, an exemplary functional schematic diagram of oneembodiment of a multi-axis suspension system is illustrated. It shouldbe noted, that orientation of components in FIG. 4A do not necessarilydenote their spatial configuration, but rather represent theirfunctional relationship with respect to one another. Explanation of theoperation of the multi-axis suspension system of FIG. 4A is facilitatedin view of FIGS. 1A, 1C, and 2-3. Pneumatic support components 302 and304 are coupled between platform 120 and the bottom portion of mountingenclosure 122 to provide a vertical component of support alongdirectional vectors 440 and 470, while also providing flexibility ofmovement along longitudinal axis 442.

Position detectors 428 and 464 utilize, for example, magnetic sensors430,432 and 466,468 to maintain mounting enclosure 122 within a range ofmovement illustrated by vertical directional vectors 440 and 470. Inparticular, position signals 434 and 474 provide an indication to acontrol unit (not shown) associated with compressors 436 and 472,respectively, as to the position of mounting enclosure 122 relative tosupport enclosure 202. If the position of mounting enclosure 122 iscentered between sensors 430 and 432, for example, then pneumaticsupport 302 is considered to be in an equilibrium position and nofurther action is taken. Similarly, if the position of mountingenclosure 122 is centered between sensors 466 and 468, for example, thenpneumatic support 304 is considered to be in an equilibrium position andno further action is taken.

If, however, the position of mounting enclosure 122 indicates a position440 that is below equilibrium, then position signal 434 provides therequisite indication to the control unit (not shown) associated withcompressor 436 to correct the over-weight condition. In particular,position signal 434 causes compressor 436 to inflate pneumatic support302, i.e., increase pressure, via line 438 until pneumatic support 302is inflated to the equilibrium position. Similarly, if the position ofmounting enclosure 122 indicates a position 470 that is belowequilibrium, then position signal 474 provides the requisite indicationto the control unit (not shown) associated with compressor 472 tocorrect the over-weight condition. In particular, position signal 474causes compressor 472 to inflate pneumatic support 304, i.e., increasepressure, via line 476 until pneumatic support 304 is inflated to theequilibrium position.

If, on the other hand, the position of mounting enclosure 122 indicatesa position 440 that is above equilibrium, then position signal 434provides the requisite indication to compressor 436 to correct theunder-weight condition. In particular, position signal 434 causes thecontrol unit (not shown) associated with compressor 436 to deflatepneumatic support 302, i.e., decrease pressure, via line 438 untilpneumatic support 302 is deflated to the equilibrium position.Similarly, if the position of mounting enclosure 122 indicates aposition 470 that is above equilibrium, then position signal 474provides the requisite indication to the control unit (not shown)associated with compressor 472 to correct the under-weight condition. Inparticular, position signal 474 causes compressor 472 to deflatepneumatic support 304, i.e., decrease pressure, via line 476 untilpneumatic support 304 is deflated to an equilibrium position.

It should be noted, that pneumatic supports 302 and 304 may operateindependently of one another. That is to say, for example, that theextent of inflation/deflation of pneumatic supports 302 and 304 may beunequal, so that unequal weight distribution of mounting enclosure 122and its associated payload (not shown) along longitudinal axis 442 maynevertheless be equalized. Thus, irregardless of the weightdistribution, the position of mounting enclosure 122 may besubstantially leveled with respect to support enclosure 202 and/orplatform 120 to implement a first mode, or coarse, suspension control.

Acting in conjunction with pneumatic supports 302 and 304, is the secondmode, or fine, suspension control. Fine suspension along directionalvectors 440 and 470 is implemented by, for example, an MR support asexemplified by components 480-484 and MR damper control components486-490. It should be noted, that the MR support as exemplified bycomponents 480-484 actuate along a vertical axis that is aligned withdirectional vectors 440 and 470. That is to say, for example, thatpiston 484 extends and retracts through a stroke of motion that issubstantially parallel with directional vectors 440 and 470.

In operation, piston 484 extends and retracts through its stroke ofmotion, while being subjected to a variable damper force. In particular,monotube housing 482 is filled with an MR fluid and is surrounded bymagnetic coil 480. The magnetic field created by magnetic coil 480causes a viscosity change in the MR fluid to exert a programmable rangeof damper forces on piston 484, where the viscosity changes in the MRfluid are effected by applying a variable magnitude of AC current tomagnetic coil 480.

In operation, PWM 490 may receive either a primarily static, or aprimarily dynamic, control signal from one of two PWM control sources.In a first embodiment, PWM 490 receives a primarily static controlsignal from potentiometer 488, which is then used to statically programa PWM signal having a duty cycle that is proportional to the staticallyprogrammed control signal from potentiometer 488. If low damper force isrequired, for example, then the appropriate control signal frompotentiometer 488 may be statically programmed to produce a relativelylow duty cycle, PWM signal. In response, a relatively low magnitude ofAC current is imparted to magnetic coil 480, which in turn imparts arelatively low magnitude magnetic field around monotube housing 482.Accordingly, the MR fluid contained within monotube housing 482reactively assumes a relatively low viscosity, which in turn provides arelatively low damper force to oppose the movement of piston 484.

If a relatively greater damper force is required, on the other hand,then the appropriate control signal from potentiometer 488 may bestatically programmed to cause PWM 490 to transmit a relatively highduty cycle, PWM signal. In response, a relatively high magnitude of ACcurrent is imparted to magnetic coil 480, which in turn imparts arelatively high magnitude magnetic field around monotube housing 482.Accordingly, the MR fluid contained within monotube housing 482reactively assumes a relatively high viscosity, which in turn provides arelatively high damper force opposing the movement of piston 484.

In an alternate embodiment, a primarily dynamic control signal isprovided to PWM 490, to effect an adaptively programmed mode ofsuspension, which is effective to isolate mounting enclosure 122 and itsassociated payload (not shown) from low frequency vibration operating inthe range of a few cycles per second to several hundred cycles persecond. In operation, accelerometer 486 measures acceleration forcesalong directional vectors 440 and 470 and provides an adaptive controlsignal to PWM 490 that is indicative of the acceleration forcesmeasured. A low magnitude of instantaneous acceleration force may resultin an adaptively programmed low duty cycle PWM signal, whereas a highmagnitude of instantaneous acceleration force may result in anadaptively programmed high duty cycle PWM signal. Thus, accelerationforces across a wide vibration bandwidth may be adaptively dampenedthrough the adaptive feedback provided by accelerometer 486 to PWM 490.The viscosity of the MR fluid then reacts to the corresponding changesin the magnetic field to exert proportional damper forces on piston 484as discussed above.

It can be seen, therefore, that pneumatic supports 302 and 304 combinewith MR support functions associated with components 480-490 to providecoarse and fine suspension control. Coarse suspension control isprovided by pneumatic supports 302 and 304 to provide weight managementof mounting enclosure 122 and its associated payload (not shown). Oncethe position of mounting enclosure 122 has been substantially equalizedwith respect to support enclosure 202 and/or platform 120, then finesuspension control is implemented via components 480-490 to “fine tune”the position in either of a programmably static, or adaptive, fashion.

MR supports may also be used to isolate kinetic energy from beingtransferred to mounting enclosure 122 and its associated payload (notshown) along a longitudinal axis depicted by directional vector 442. Inparticular, components 416-426 may combine to form MR support 204 ofFIG. 2 to implement either programmably static or adaptive isolationfrom kinetic energy along directional vector 442. Additionally,components 452-462 may combine to form MR support 206 of FIG. 2 toimplement either programmably static or adaptive isolation from kineticenergy along directional vector 442. Operation of components 416-426 andcomponents 452-462 operate substantially as discussed above in relationto components 480-490 in either of a programmably static, or adaptive,fashion.

A third component of suspension may also be provided for mountingenclosure 122 and its associated payload (not shown). In particular, acomponent of suspension may be provided along a directional vector thatis orthogonal to directional vectors 440, 470, and 442. The suspension,for example, may also be provided via MR supports, as discussed above,to provide a third axis of suspension to substantially eliminate kineticenergy transfer along a lateral axis relative to mounting enclosure 122.

Turning to FIG. 4B, an alternate embodiment of a multi-axis suspensionsystem is exemplified. As discussed above, supports 204 and 206 (andother supports, if needed) may be comprised of both MR supports andpneumatic spring supports. Air piston 407, air reservoir 405, compressor403, and control block 401 combine to form the programmable pneumaticspring of support 204, while air piston 415, air reservoir 413,compressor 411, and control block 409 combine to form the programmablepneumatic spring of support 206.

Through interaction of each air piston, air reservoir, and controlmodule, i.e., the programmable pneumatic spring, any variation of theposition of mounting enclosure 122 relative to structural enclosure 202along longitudinal axis 442 may be opposed. As such, the air piston/airreservoir combination operates as a position equalization device tomaintain the position of mounting enclosure 122 within an equilibriumposition relative to structural enclosure 202 along longitudinal axis442.

Air reservoirs 405 and 413 may be filled to a nominal air pressure, viacompressors 403 and 411, respectively, to maintain an equilibrium lengthof air pistons 407 and 415. Once an equilibrium length of air pistons407 and 415 has been established, minute variations in the length of airpistons 407 and 415 may be substantially absorbed through the elasticityof the walls of air reservoirs 405 and 413. In one embodiment, forexample, the walls of air reservoirs 405 and 413 may be constructed ofan elastic composition, such as rubber, to allow expansion andcontraction of the walls of air reservoirs 405 and 413. Air tubingconnecting air pistons 407,415 to air reservoirs 405,413, facilitates afree-flow of air to be exchanged, such that air forced out of airpistons 407 and 415 during contraction may be collected by airreservoirs 405 and 413, respectively, and air required by air pistons407 and 415 during expansion may be provided by air reservoirs 405 and413, respectively.

As such, a slight contraction of air pistons 407 and 415 along axis 442causes a responsive slight expansion of the walls of air reservoirs 405and 413. Conversely, a slight expansion of air pistons 407 and 415 alongaxis 442 causes a responsive slight contraction of the walls of airreservoirs 405 and 413. Thus, a spring-like operation is created throughthe interaction of air pistons 407,415 and air reservoirs 405,413,whereby the elasticity of the walls of air reservoirs 405,413 serves toabsorb minute variations in the length of air pistons 407,415. As such,the pneumatic springs of supports 204 and 206 seek to center mountingenclosure 122 within structural enclosure 202 along longitudinal axis442.

Control blocks 401 and 409 may additionally provide other features. Inparticular, a sleep mode may be provided, whereby all operational powerto the suspension system may be gated off to provide a powerconservation mode. A wake-up feature may also be provided, whereby forexample, a piezoelectric sensor (not shown) detects movement of themobile electronic equipment rack during the sleep mode. Once awakened,operational power may be restored and sensors 428 and 464, or some otherweight sensor, may be queried by control blocks 401 and 409 for weightinformation relating to the weight of mounting enclosure 122 andassociated payload. Once known, the weight information may be utilizedby control blocks 401 and 409 to individually program potentiometers424, 460, and 488, or accelerometers 426, 462, and 486, to select thedamper resistance of their respective MR supports to an optimal damperresistance value that is based upon the weight measurement.

In an alternate embodiment, signal LOAD may be received from an externalsource that is indicative of weight information relating to the weightof mounting enclosure 122 and associated payload. The weight informationprovided by signal LOAD may then be utilized by control blocks 401 and409 to individually program potentiometers 424, 460, and 488, oraccelerometers 426, 462, and 486, to select the damper resistance oftheir respective MR supports to an optimal resistance value that isbased upon signal LOAD. It should be noted, that the damper resistanceof each MR support may be individually programmed by control blocks 401and 409 as necessary.

As discussed above, adaptive fine suspension control may be effected todampen kinetic energy transfer to mounting enclosure 122. Accelerometers426, 462, and 486 may be implemented to detect, and subsequentlyprovide, an acceleration feedback control signal that is indicative ofthe time-varying attributes of acceleration excitations being applied tomounting enclosure 122. Control blocks 401,409 may then continuallyanalyze the acceleration feedback control signals to determine thenature of the acceleration forces being applied.

For example, control blocks 401,409 may apply a fast Fourier transform(FFT) to the acceleration feedback control signals provided byaccelerometers 426, 462, and 486 to determine the spectral content ofvibration that is generated by the acceleration excitations. As such,fine suspension control may be adapted through the FFT analysis ofcontrol blocks 401,409 to provide wide vibration bandwidth isolation tomounting enclosure 122.

Harmonic components of vibration may also be analyzed to determine thetime varying characteristics of the vibration. In particular, the powerspectra of the vibration may be analyzed using the FFT algorithm todetermine signal strength in designated frequency bands, i.e., FFT bins,of the FFT output. A quantitative relationship between the vibrationamplitude in the time domain and the associated spectral amplitude inthe frequency domain may then be obtained to optimize the kinetic energyabsorption performance.

For example, if the power spectra of the vibration is confined torelatively few FFT bins, then the acceleration excitation may becharacterized as a steady state excitation having a sinusoidal propertycentered about a substantially constant frequency. As such, the finesuspension devices of supports 204, 206, and 492 may be optimized todampen vibration at the steady state excitation frequency by appropriatecontrol of its damper force via control blocks 401,409.

If the power spectra of the vibration is not confined to a relativelyfew FFT bins, but is rather spread out across multiple FFT bins, thenthe acceleration excitation may instead be characterized as a stepchange in mounting enclosure 122 displacement, such as may be caused bytraversing rough terrain. In such an instance, the damper force of thefine suspension devices of supports 204, 206, and 492 may be increasedby control blocks 401,409 for optimum damper force at fundamental andharmonic frequencies of vibration excitation. Once the vibration impulseis dampened, control blocks 401,409 may return the fine suspensiondevices of supports 204, 206, and 492 to a steady state mode ofoperation.

In addition, control blocks 401,409 may continuously process FFT data toachieve a quiescent mode of operation, whereby optimized kinetic energyabsorption across a wide bandwidth of vibration excitation may befurther facilitated. That is to say, for example, that averaging of theFFT data may yield an optimized suspension control signal from controlblocks 401,409, such that the damper force of the fine suspensiondevices of supports 204, 206, and 492 may be maintained at a nominallevel between the steady state response and the step change response asdiscussed above.

Optimized suspension control in this context means that the reactiontime of the fine suspension devices of supports 204, 206, and 492 isminimized due to the quiescent mode of operation. In particular, sincethe fine suspension devices of supports 204, 206, and 492 are programmedto exhibit a nominal damper force, the reaction time to achieve minimumor maximum damper resistance is essentially cut in half, assuming thatthe nominal damper force selected represents an average damper forceacross the entire dynamic range of damper force of the fine suspensiondevices of supports 204, 206, and 492.

In addition, weight information received by control blocks 401,409 fromsensors 428,464, signal LOAD, or from some other weight sensing device,may also be used to program the nominal damper resistance. Inparticular, performance of the fine suspension devices of supports 204,206, and 492 may be optimized by selecting a nominal damper resistancethat is proportional to the weight of mounting enclosure 122.

As discussed above, a layer of elastomeric material 451 may be usedbetween supports 204, 206, 302, 304 and their respective mountingsurfaces to provide additional vibration/shock absorption. Furthermore,elastomeric compounds having varying resonant frequencies may beselected to optimize the operation of the suspension system. Forexample, given that the MR dampers are responsive up to a nominalfrequency of, e.g., 40 hertz, the resonant frequency of the elastomericmaterial may be individually selected to be higher than the operationalfrequency range of the MR dampers. Thus, by appropriate staggering ofresonant frequencies, each individual elastomeric mount 451 may beselected to extend the operational bandwidth of the suspension system towell beyond the operational frequency range of the MR dampers.

Turning to FIG. 5, an alternate embodiment is exemplified in which avertical component of suspension along directional vectors 440 and 470is provided in a space saving fashion. In particular, the verticalcomponent of suspension is provided in a manner that minimizes theamount of vertical space required between mounting enclosure 122 andplatform 120. It should be noted, that the pneumatic spring mechanismsdiscussed above in relation to FIG. 4B, operate in the same manner asillustrated in FIG. 5 and will not be discussed in relation to FIG. 5.

In operation, coarse position control is implemented by pneumaticsupports 302 and 304 to maintain an equilibrium position of mountingenclosure 122 with respect to support enclosure 202 along directionalvectors 440 and 470 as discussed above in relation to FIG. 4. Fineposition control, however, utilizes an MR support that is not fixed in avertical relationship with respect to mounting enclosure 122. Instead,the MR support is coupled between support enclosure 202 and/or platform120 and right-angle gear drive 528 to reduce the vertical relationshipof the MR support between mounting enclosure 122 and platform 120.

As such, actuation of the MR support does not extend piston 520 along arange of stroke whose direction is parallel to directional vectors 440and 470. Instead, piston 520 extends along a range of stroke whosedirection may range between one that is orthogonal to directionalvectors 440 and 470 and one that is just short of parallel todirectional vectors 440 and 470. As the direction of the range of strokeof piston 520 approaches one that is orthogonal to directional vectors440 and 470, the amount of vertical space required between mountingenclosure 122 and platform 120 reduces in proportion to the sine of theangle formed between the direction of stroke of piston 520 and platform120.

In operation, the range of stroke of piston 520 actuates right-anglegear drive 528 to rotate right-angle gear drive 528 in a direction thatis indicated by rotational vector 522. An upward movement of mountingenclosure 122, for example, may cause piston 530 to extend. In response,right-angle gear drive 528 may rotate clockwise to cause piston 520 toextend. However, the movement of piston 520 is resisted by the damperforce exerted by the associated MR fluid surrounding piston 520 asdiscussed above. As such, an upward movement of mounting enclosure 122is resisted by MR piston 520 through rotational actuation of right-anglegear drive 528.

A downward movement of mounting enclosure 122, on the other hand, maycause piston 530 to retract. In response, right-angle gear drive 528 mayrotate counter-clockwise to cause piston 520 to retract. However, themovement of piston 520 is resisted by the damper force exerted by theassociated MR fluid surrounding piston 520 as discussed above. As such,a downward movement of mounting enclosure 122 is resisted by MR piston520 through rotational actuation of right-angle gear drive 528.

As discussed above in relation to components 480-490 of FIG. 4A, avariable damper force may either be programmably static, or adaptive,when applied to piston 520 to effectuate “fine tuned” MR suspensioncontrol, while minimizing the vertical separation required betweenmounting enclosure 122 and platform 120 through the utilization of rightangle gear drive 528.

Turning to FIG. 6A, a method of coarse suspension control is exemplifiedvia flow diagram 600 and is described in relation to FIGS. 4A, 4B, and5. In step 602, a position of mounting enclosure 122 is detected viamagnetic sensors 430,432 and 466,468 during, for example, a wake-up modeas discussed above. Since the weight distribution along a longitudinalaxis depicted by directional vector 442 may be non-uniform, sensors430,432 detect vertical movement along a vertical axis depicted bydirectional vector 440 and sensors 466,468 independently measurevertical movement along a vertical axis depicted by directional vector470.

Should mounting enclosure 122 be deflected below its equilibriumposition, as detected in step 604 by either of sensors 430,432 and/or466,468, then signal 434 and/or signal 474 is dispatched to compressors436 and/or 472 to counteract the downward displacement. In particular,compressors 436 and/or 472 inject air into pneumatic support components302 and/or 304 in response to signals 434 and/or 474 to increase themagnitude of coarse suspension provided to mounting enclosure 122 as instep 606.

Should mounting enclosure 122 be deflected above its equilibriumposition on the other hand, as detected in step 608 by either of sensors430,432 and/or 466,468, then signal 434 and/or signal 474 is dispatchedto compressors 436 and/or 472 to counteract the upward displacement. Inparticular, release valves within compressors 436 and/or 472 cause airto be released from pneumatic support components 302 and/or 304 inresponse to signals 434 and/or 474 to decrease the magnitude of coarsesuspension provided to mounting enclosure 122 as in step 610.

Turning to FIG. 6B, a method of fine suspension control is exemplifiedvia flow diagram 650 and is described in relation to FIGS. 4A, 4B, and5. In step 652, detection of acceleration forces is either activated ordeactivated. If activated, then accelerometers 486, 426, and 462 areselected in step 656 to provide adaptive control signals to PWMs 490,422, and 458, respectively, to indicate the magnitude and direction ofacceleration forces measured for appropriate selection of damperresistance. If deactivated, on the other hand, then acceleration forcesare not detected and potentiometers 488, 424, and 460 are selected instep 654 to provide programmably static control signals for staticselection of damper resistance.

In addition, a weight measurement is taken, whereby weight informationreceived by control blocks 401,409 from sensors 428,464, signal LOAD, orfrom some other weight sensing device, may be used to program thenominal damper resistance. In particular, performance of the finesuspension devices of supports 204, 206, and 492 may be optimized byselecting a nominal damper resistance that is proportional to the weightof mounting enclosure 122 in either of the dynamic or static controlmodes.

If vertical movement is detected in step 658, then either a low-profile,or a normal profile, mode of vertical suspension is provided. Ifvertical suspension is provided as exemplified in FIG. 4A, then kineticenergy is dampened through substantially vertical actuation of MR piston484 as in step 662. The amount of damper resistance applied to piston484 being determined in either of steps 654 or 656 as discussed above.

If, on the other hand, vertical suspension is provided as exemplified inFIG. 5, then kinetic energy is dampened through rotational actuation ofMR piston 520 to implement a low-profile mode of vertical suspension. Inparticular, the range of stroke of piston 520 actuates right-angle geardrive 528 to rotate right-angle gear drive 528 in a direction that isindicated by rotational vector 522. An upward movement of mountingenclosure 122, for example, may cause piston 530 to extend. In response,right-angle gear drive 528 may rotate clockwise to cause piston 520 toextend. However, the movement of piston 520 is resisted by the damperforce exerted by the associated MR fluid surrounding piston 520 asdiscussed above. As such, an upward movement of mounting enclosure 122is resisted by MR piston 520 through rotational actuation of right-anglegear drive 528.

A downward movement of mounting enclosure 122, on the other hand, maycause piston 530 to retract. In response, right-angle gear drive 528 mayrotate counter-clockwise to cause piston 520 to retract. However, themovement of piston 520 is resisted by the damper force exerted by theassociated MR fluid surrounding piston 520 as discussed above. As such,a downward movement of mounting enclosure 122 is resisted by MR piston520 through rotational actuation of right-angle gear drive 528. Theamount of damper resistance applied to piston 520 being determined ineither of steps 654 or 656 as discussed above.

Kinetic energy, as determined in step 668, may also be dampened along alongitudinal axis as depicted by directional vector 442. In particular,both sides of mounting enclosure 122 are “soft” mounted to structuralenclosure 202 through MR supports 204 and 206. Damper resistance of MRsupports 204 and 206 may be adaptively, or statically, programmed asdiscussed above. In operation, MR supports 204 and 206 substantiallyabsorb kinetic energy in step 670 that is applied to mounting enclosure122 along a longitudinal direction as depicted by directional vector442. In step 672, pneumatic springs, as discussed above in relation toFIG. 4B, operate to maintain mounting enclosure 122 within anequilibrium position with respect to structural enclosure 202 alonglongitudinal axis 442.

Other aspects and embodiments of the present invention will be apparentto those skilled in the art from consideration of the specification andpractice of the invention disclosed herein. For example, the payloadinstalled within mounting enclosure 122 may not necessarily correspondto electronic components. Rather, the payload may instead correspond toother shock sensitive materials, such as nitroglycerin, which requirestransportation mechanisms that minimize the amount of kinetic energytransferred, so as to minimize the possibility of premature detonation.Protection against premature detonation may be further provided byenvironment proof enclosure 102 when constructed with armored materialsas discussed above.

Furthermore, items requiring a fixed storage temperature range, such asfood, drink, or other temperature sensitive items, may also betransported in an environment that is temperature controlled andvirtually free from multi-dimensional acceleration forces. Additionally,while the mobile enclosures exemplified herein provide forself-propulsion, it is appreciated that mobility control device 106 ofFIG. 1 may instead be eliminated as exemplified in FIGS. 2 and 3. Assuch, non-mobile enclosures, such as may be required in maritime,aeronautical, or seismic applications, may be provided to implementkinetic energy isolation for the payload contained within the non-mobileenclosures. In such instances, the non-mobile enclosures of FIGS. 2 and3 may instead be mounted directly to a platform, e.g., floor space, asmay be provided by the particular non-mobile application, such as in anequipment room of a telecommunications facility. It is intended,therefore, that the specification and illustrated embodiments beconsidered as examples only, with a true scope and spirit of theinvention being indicated by the following claims.

What is claimed is:
 1. A pneumatically sprung caster, comprising: acaster, the caster being adapted to rotate about an axis of the caster;a pivoting axle having a first end coupled to the axis of the caster anda second end coupled to a support structure, the caster, pivoting axleand support structure being adapted to swivel in a circular direction;an air bladder coupled to the pivoting axle; a valve coupled to the airbladder; a reservoir coupled to the valve; wherein an equilibrium lengthof the air bladder is adjusted in response to actuation of the valve toreceive air from the reservoir or exhaust air from the air bladder toadjust a height of the support structure; a first switch magneticallycoupled to the air bladder and adapted to detect a first length of theair bladder; and a second switch magnetically coupled to the air bladderand adapted to detect a second length of the air bladder.
 2. Thepneumatically sprung caster of claim 1, further comprising a contactplatform coupled to the support structure, the contact platformincluding, a first surface having a plurality of conductive tracesarranged as concentric circles; and a second surface having a pluralityof electrical contacts, each electrical contact being coupled to acorresponding conductive trace.
 3. The pneumatically sprung caster ofclaim 2, further comprising a controller movably coupled to the firstsurface of the contact platform, wherein electrical contact ismaintained between the controller and each conductive trace of thecontact platform during caster rotation.
 4. The pneumatically sprungcaster of claim 3, further comprising a compressor coupled to thereservoir to maintain a threshold amount of air pressure within thereservoir.
 5. A pneumatically sprung caster, comprising: a caster, thecaster being adapted to rotate about an axis of the caster; a pivotingaxle having a first end coupled to the axis of the caster and a secondend coupled to a support structure, the caster, pivoting axle andsupport structure being adapted to swivel in a circular direction; anair bladder coupled to the pivoting axle; a valve coupled to the airbladder; a reservoir coupled to the valve, wherein an equilibrium lengthof the air bladder is adjusted in response to actuation of the valve toreceive air from the reservoir or exhaust air from the air bladder toadjust a height of the support structure; a contact platform coupled tothe support structure, the contact platform including, a first surfacehaving a plurality of conductive traces arranged as concentric circles;and a second surface having a plurality of electrical contacts, eachelectrical contact being coupled to a corresponding conductive trace;and a controller movably coupled to the first surface of the contactplatform, wherein electrical contact is maintained between thecontroller and each conductive trace of the contact platform duringcaster rotation.
 6. The pneumatically sprung caster of claim 5, furthercomprising: a first switch magnetically coupled to the air bladder andadapted to detect a first length of the air bladder; and a second switchmagnetically coupled to the air bladder and adapted to detect a secondlength of the air bladder.
 7. The pneumatically sprung caster of claim5, further comprising a compressor coupled to the reservoir to maintaina threshold amount of air pressure within the reservoir.
 8. Apneumatically sprung caster, comprising: a caster, the caster beingadapted to rotate about an axis of the caster; a pivoting axle having afirst end coupled to the axis of the caster and a second end coupled toa support structure, the caster, pivoting axle and support structurebeing adapted to swivel in a circular direction; an air bladder coupledto the pivoting axle; a valve coupled to the air bladder; a reservoircoupled to the valve, wherein an equilibrium length of the air bladderis adjusted in response to actuation of the valve to receive air fromthe reservoir or exhaust air from the air bladder to adjust a height ofthe support structure; a contact platform coupled to the supportstructure, the contact platform including, a first surface having aplurality of conductive traces arranged as concentric circles; and asecond surface having a plurality of electrical contacts, eachelectrical contact being coupled to a corresponding conductive trace. 9.The pneumatically sprung caster of claim 7, further comprising acontroller movably coupled to the first surface of the contact platform,wherein electrical contact is maintained between the controller and eachconductive trace of the contact platform during caster rotation.
 10. Thepneumatically sprung caster of claim 7, further comprising: a firstswitch magnetically coupled to the air bladder and adapted to detect afirst length of the air bladder; and a second switch magneticallycoupled to the air bladder and adapted to detect a second length of theair bladder.
 11. The pneumatically sprung caster of claim 7, furthercomprising a compressor coupled to the reservoir to maintain a thresholdamount of air pressure within the reservoir.